METHOD OF CLEANING OF NEAR WELLBORE REGION OF INJECTION WELLS Russian patent published in 2015 - IPC E21B37/00 

FIELD: oil-and-gas industry.

SUBSTANCE: at wellhead the string is equipped at bottom with blind filter, above the filter the mechanical packer is installed, above it a drain valve is installed, string is lowered in the well such that packer will be above the formation, and filter will be below the formation perforation interval. Backflow washing is performed by surface-active substance solution under accelerated mode, the packer is installed. The string head is installed at wellhead, chokes with valves are installed on it. The choke bores increase in upward direction. The hydraulic swabbing in performed by cycles depending on number of chokes with the solvent periodic injection to the formation via the string with gradual injection overpressure increasing during each cycle, excluding the hydraulic fracturing of the formation, and leak of the formation injected solvent via the string through the choke to tank in wellhead zone of the well. Upon the hydraulic swabbing completion the drain valve is destructed and above packer space is connected with the string via the drain valve hole, the liquid is swabbed from the tubing-casing annulus of the well through the string. Packer is released and removed with string from the well.

EFFECT: improved cleaning efficiency and possibility to monitor the process, hydraulic impact is excluded.

1 dwg